Surface treating machine with controlled delivery

ABSTRACT

A surface treatment machine, comprising a frame configured to translate with respect to a surface to treat, a surface treatment element connected to said frame and configured to treat with liquid a surface, a reservoir connected to the frame to provide liquid to the surface treatment element through a delivery mouth; an adjustment element arranged to feed adjustably the liquid supplied from the reservoir to the delivery mouth. A sensor is configured to measure an operating parameter P of the machine, such as the level of residual liquid in the reservoir, or the flow-rate of the liquid from said reservoir towards the delivery mouth, or the speed of the machine. A control unit receives by the sensor a signal proportional to operating parameter P and for adjusting the adjustment element responsive to operating parameter P, in order to deliver the liquid according to a predetermined function f(P) of optimization of the flow-rate. It is possible then to maximize the range of the machine, and to optimize the working time of the operator.

FIELD OF THE INVENTION

The present invention relates to surface treating machines of the type having a surface treatment element configured to treat the surface with liquid.

Among such machines there are comprised both those of ride-on type and of walk-behind type, which can be either motorized or pushed, with surface treatment element in the form of either a brush, disc, pad, spraying member.

DESCRIPTION OF THE PRIOR ART

Machines exist for treating surfaces with liquid that provide the application of the liquid by means of a treatment element, taking the liquid from a reservoir on board of the machine.

Once ended the liquid, the operator has to bring normally the machine to a point of replenishment, for filling again the reservoir.

In some cases the dirty liquid is collected from the surface by the same machine, for example by a suction system, which drains the liquid by suction up to a collection container on board of the machine. When the reservoir is emptied also the collection container is normally full, because the latter is sized according to the capacity of the reservoir.

The operators of such surface treating machines, in case they have to cover wide surfaces, like the case for example of overnight cleaning of places like airports, hospitals, schools, offices, etc., have often the problem of not knowing, unless in very rough approximation, the amount of residual liquid in the reservoir, and then the range of the machine in terms of amount of surface that can be treated before making again a replenishment of liquid.

A precise knowledge of the range of the machine is desirable, because it would allow planning an optimal treatment route up, to the nearest replenishment point before the treatment liquid finishes.

In WO2010/099968A2 a machine for cleaning surfaces is described that provides a system for automatically calculating the range of the machine. It carries out a measurement of physical and kinematical quantities, in particular the translation speed of the machine, from which the ratio is calculated between the cleaned surface and time necessary to clean it, responsive to many parameters indicated by the operator, like the size of the brush or the size of the nozzle for soaking the brush. The operator, by knowing the residual range of the machine, has a useful information for completing the route up to the next replenishment.

In the surface treating machines with liquid treatment it can occur that the delivery of liquid to the surface treatment element is not fixed, and this does not allow to calculate the range of the machine precisely with an easy knowledge of physical and kinematical quantities, as space, time, speed.

For example, in case of feeding the liquid by gravity, as the reservoir is progressively emptied the flow-rate of liquid to the treatment element changes. Even in case of feeding the liquid by means of a pump not of positive displacement type, which however would be heavier and expensive, the flow-rate of liquid to the surface treatment element can change, owing to leakages and to sensitivity of the pump to the supply pressure. The operator, then, in order ensure an effective treatment, i.e. with a sufficient amount of liquid versus treated surface, adjusts the opening value of the feeding duct section in such a way to ensure always an amount of liquid vis-a-vis treated surface that is enough for treatment also in the most unfavorable situations. This determines, however, owing to unsteadiness of the flow-rate, a reduction of the range of the machine.

Furthermore, changing the translation speed of the surface treating machines with respect to the surface to treat, there is a subsequent change of the amount of supplied liquid versus treated surface, and also this requires an adjustment of the feeding duct section, in order to ensure an amount of liquid that is sufficient also in case of maximum translation speed of the machine, with the consequence of reducing the range of the machine.

In U.S. Pat. No. 8,551,262 the chemical detergent is dosed with respect to water, taking into account the level in the water reservoir. A level sensor provides a signal of level that influences a controller of a positive displacement pump which feeds the chemical detergent. This way, the dilution in water of the chemical detergent is kept fixed regardless of the level of water reservoir.

US2007/192973 describes a surface treatment machine which uses a cleaning liquid that is supplied by a system containing at least two reservoirs, one for a dilution fluid and another for a concentrated chemical detergent. A system provides controlled metering of liquid in proportion to the concentrated chemical detergent to obtain a cleaning solution with desired concentration.

SUMMARY OF THE INVENTION

It is a feature of the present invention to provide a surface treatment machine that ensures an effective treatment vis-a-vis the amount of liquid versus treated surface and in the meantime maximizes the range of the machine.

It is another feature of the invention to provide such a machine which permits controlling the delivery of liquid to the surface treatment element versus the level of liquid present in the reservoir for improving the range of the machine.

It is another feature of the invention to provide such a machine for having the same treatment efficiency, concerning liquid versus treated surface, and versus the translation speed of the machine.

It is also a feature of the present invention to provide such a machine that enables an operator to determine in real time the residual range of the machine.

These and other objects are achieved by a surface treating machine, comprising:

-   -   a frame configured to translate with respect to a surface to         treat,     -   a surface treatment element connected to the frame and         configured to treat with liquid a surface with respect to which         the frame advances,     -   a reservoir connected to the frame and arranged to provide         liquid to the surface treatment element through a delivery         mouth;     -   an adjustment element arranged to adjustably pulse-feed the         liquid supplied from the reservoir to the delivery mouth;     -   a sensor configured to measure an operating parameter P of the         machine, selected from the group consisting of: level P₁ of         residual liquid in the reservoir, actual flow-rate P₂ of the         liquid from the reservoir towards the delivery mouth         simultaneously to the pulse-feed step of liquid, translational         speed P₃ of the machine relatively to the surface, or a         combination thereof;     -   a control unit configured to receive from the sensor a signal         proportional to operating parameter P and configured to set the         adjustment element responsive to operating parameter P, in order         to pulse-feed the liquid with a duty cycle t%, expressed as a         ratio between the duration of a pulse of the pulse-feed step and         the time between two consecutive pulses, determined according to         a predetermined function t%=f(P) of optimization of the         flow-rate, wherein said function f(P) is selected from the group         consisting of:

t%=f (P₁)=K1*P₁ ^(−1/2)  (1)

t%=f (P₂)=K₂*P₂ ⁻¹  (2)

t%=f (P₃)=K₃*P₃  (3)

This way, once calculated function f(P), the control unit adjusts automatically the adjustment element so that it provides an amount of liquid versus time responsive to changes of operating parameter P.

In the case, for example, where operating parameter P is the level P₁ of residual liquid present in the reservoir, since the level influences the amount of liquid supplied by the different head of residual liquid in the reservoir at an outlet section thereof, the lower the level of residual liquid and the lower the amount of liquid dispensed, in a non-linear way, but determinable according to the geometry of the duct, and to the features of the adjustment element. Therefore, function f(P₁) is configured to keep as far as possible fixed the amount of liquid supplied so that the undesirable effect of delivery affected by the level of liquid in the reservoir is eliminated and the flow-rate is optimized, achieving the goal of maximizing the range of the machine responsive to the remaining space to be treated up to reaching a programmed replenishment point. In other words, function f(P) is inputted with the distance to be covered or surface to be covered up to the point of replenishment and is configured to adjust the flow-rate so that the machine carries out the treatment up to such point avoiding shortage of liquid.

In the case, instead, where operating parameter P is the flow-rate P₂ of the liquid at the outlet of the reservoir, then function f(P) is configured to keep as far as possible the flow-rate constant, i.e. a control in closed loop flow-rate feedback, so that it meets a predetermined range chosen by the operator, so that the flow-rate is independent from external factors that can influence it.

In the case, always for example, where operating parameter P is the translation speed of the machine, then function f(P) is determined so that the amount of supplied liquid versus treated surface is constant, whichever is the speed. Therefore, at a lower speed the control unit would set the adjustment element so that the ratio between amount of liquid actually supplied and treated surface versus time meets a predetermined value.

Advantageously, if operating parameter P is a measurement of the level of liquid present in the reservoir, the parameter P is proportional to the amount of liquid present in the reservoir, and for example is a pressure value P₁, and the sensor is a sensor of pressure that is communicating with the reservoir for determining the level of liquid present in the reservoir.

This solution allows a very precise control of the level in the liquid in the reservoir. In fact, a pressure sensor located at the base of the reservoir, after filtering fluctuations due to the movement of the machine that are eliminable as noise, gives a precise value of the level, which can influence the flow-rate, i.e. the hydrostatic pressure, owing to the head liquid in the reservoir, in order to optimize the flow-rate.

Alternatively, the level of liquid present in the reservoir can be determined with a force sensor, in particular a load cell, which can be arranged to hold the weight of support elements of said reservoir.

Alternatively, the level of liquid present in the reservoir can be determined with a level sensor, in particular an optical sensor or ultrasonic pulse sensor or floating sensor, which is located in said reservoir, and configured to measure the distance of the liquid surface of the liquid from the bottom or from a top wall of the reservoir.

In a possible exemplary embodiment, where the parameter P is a value P₁ proportional to an amount or level of liquid present in the reservoir, the adjustment element is selected from the group consisting of:

-   -   a piloted valve, where the control unit is configured to         pulse-feed the liquid, with a predetermined duty cycle t%, by         adjusting the opening time of the adjustment valve in an         increasing way responsive to decrease of the level according to         function f(P₁);     -   a pump, where the control unit is configured to pulse-feed the         liquid, with a predetermined duty cycle t%, by adjusting a         pulse-feed rate of the pump in an increasing way responsive to         decrease of the level according to function f(P₁).

This way, it is eliminated the undesirable effect that causes the variation of the flow-rate of liquid supplied to the surface treatment element versus the level of liquid present in the reservoir, and the flow-rate is optimized, according to function f(P). This way the amount of supplied liquid is adjusted, in order to have an ideal treatment efficiency without excessive or insufficient liquid supply, in order to maximize the range of the machine.

In a possible exemplary embodiment, if operating parameter P is a measurement of the flow-rate of liquid that is supplied to the delivery mouth, and the sensor is a flow-rate sensor, such as a flow meter or liter-counter, which is arranged in a portion of duct between the reservoir and the delivery mouth and provides a signal P₂ proportional to the flow-rate, the adjustment element is selected from the group consisting of:

-   -   a piloted valve, where the control unit is configured to         pulse-feed the liquid, with a predetermined duty cycle t%, by         adjusting the opening time of the adjustment valve in closed         loop feedback according to function f(P₂);     -   a pump, where the control unit is configured to cause the pump         to pulse-feed the liquid, with a predetermined duty cycle t%, by         adjusting a pulse-feed rate of the pump in closed loop feedback         according to function f(P₂).

In this case, the control unit influences the adjustment element, i.e. the valve or the pump, so that there is a continuous feedback adjustment of the flow-rate, eliminating also here the causes that determine an undesired variation of the flow-rate with respect to ideal operation parameters, and optimizing the flow-rate, in order to achieve a maximum range of the machine.

If operating parameter P is a measurement of the speed P₂ of the frame of the machine with respect to the surface to treat, the sensor is a speed sensor configured to provide a value P₃ proportional to a speed of the machine, and the adjustment element is selected from the group consisting of:

-   -   a piloted valve, where the control unit is configured to cause a         pulse-feed of the liquid, with a predetermined duty cycle t%, by         adjusting the opening time of the adjustment valve in an         increasing way responsive to an increase of the translational         speed according to function f(P₃);     -   a pump, where the control unit is configured to cause the pump         to pulse-feed the liquid, with a predetermined duty cycle t%, by         adjusting a pulse-feed rate in an increasing way responsive to         an increase of the translational speed according to function         f(P₃).

This way, the delivery is ensured of an amount of liquid versus treated surface for achieving an optimal treatment of the surface, and keeping the flow-rate within the minimum necessary, such that a maximum range of the machine is obtained.

Advantageously, the frame is configured to translate with respect to the surface to treat by means of wheels, and the sensor configured to provide a value P₃ proportional to a translation speed of the machine is an encoder arranged to measure the speed of one of the wheels.

Alternatively, the frame is configured to translate with respect to the surface to treat operated by a motor, and the sensor configured to provide a value P₃ proportional to a translation speed of the machine is a sensor configured to measure the pulse-width modulation (PWM) of the motor.

In a possible exemplary embodiment, operating parameter P is a combination of a measurement P₃ of the translation speed of the frame and of a measurement P₁ of the level of liquid present in the reservoir or of a measurement P₂ of the flow-rate of liquid that is supplied to the delivery mouth, function f(P) configured to maximize the range of the machine starting from settings of the machine given by the nature of the surface and/or by environmental conditions. In a possible embodiment, responsive to the parameter P₃ function f(P₁, P₃) is configured to keep constant the amount of liquid versus treated surface regardless of the speed of the machine, whereas responsive to the parameter P₁ function f(P₁, P₃) is configured to keep constant the amount of liquid versus treated surface, regardless of the level of residual liquid present in the reservoir.

Similarly, responsive to the parameter P₂ function f(P₁, P₂) is configured to keep constant the amount of liquid versus treated surface, with a control in closed loop feedback of the flow-rate.

Advantageously, the control unit is associated with a display unit of the operating parameters and of a value of range of the machine calculated on the basis of instant values of function f(P).

This way, the operator is enabled to see on the display unit the values of residual range of the machine, versus time, or the residual surface to treat, in order to determine the optimal route that allows to reach a replenishment point without loss of time or covering useless routes.

In an embodiment the adjustment element is a piloted valve, and the reservoir is arranged with respect to the delivery mouth for delivering liquid to the surface treatment element by gravity through the valve.

This solution makes it possible to minimize the costs for making the machine, since it does not need a pump for delivering the liquid to the treatment element, but exploits simply the gravity, achieving the goal of avoiding to have an not controllable amount of supplied liquid responsive to the treated surface.

Also the operator is enabled to see on the display unit the values of residual range of the machine, versus time, or the residual surface to treat, and to set in turn the treatment route that allows maximizing the range of the machine and eventually making a replenishment without loss of time or covering useless routes. In particular, the operator can set the range of the machine so that up to the replenishment point the flow-rate of liquid is constant and all the liquid present in the reservoir is used.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be now shown with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings in which:

FIG. 1 shows a block diagram of a generic surface treatment machine according to the prior art;

FIG. 2 shows a block diagram of a generic surface treatment machine according to the invention;

FIG. 3 shows a block diagram of a first exemplary embodiment of the invention;

FIG. 4 shows a block diagram of a second exemplary embodiment of the invention;

FIG. 5 shows a block diagram of a third exemplary embodiment of the invention;

FIG. 6 shows a block diagram of a fourth exemplary embodiment of the invention.

DETAILED DESCRIPTION OF SOME EXEMPLARY EMBODIMENTS

As shown in FIG. 1, a surface treating machine, whose diagrammatical general view is known and indicated as 1, comprises a frame 11 configured to translate with respect to a surface 12 to treat.

The translation, in a in the direction of arrow 2, can be carried out by pushing, through a handlebar or through separate handles (not shown), or in a motorized way, through wheels or tracks (not shown), and the machine can be of ride-on type and of walk-behind type. Surface 12 to treat can be a floor but can also be vertical, as windows or vertical walls, moved on vertical guides or through lifting platforms (not shown).

Machine 1 comprises a surface treatment element 13 connected to the frame 11 and configured to treat with liquid surface 12 with respect to which the frame 11 advances.

The surface treatment element, indicated generally as block 13, can be a rotating brush or other brush element, as well as can be a vibrating pad or other treatment element, for example a spray liquid distributor. A motor can be provided or other actuating element 13 a for actuating a connecting element 13 b linked to the surface treatment element 13, for example a rotating shaft.

Furthermore, machine 1 comprises a reservoir 14 connected to the frame 11 and arranged to provide liquid to surface treatment element 13 through a delivery mouth 15. It is then provided an adjustment element 16 arranged to feed adjustably the liquid supplied from reservoir 14 to delivery mouth 15, and located between two branches 15 a and 15 b arranged for feeding the liquid from reservoir 14 to delivery mouth 15.

The treatment liquid in reservoir 14 can be water, water with detergent, pure detergent, or other treatment liquid, for example protecting film, coating film, etc. A further reservoir of chemical detergent can also be provided to mix with the water before the delivery (not shown).

The adjustment element indicated generally with block 16 can be a valve or a pump. It can be simply an On/Off device or an adjustable device, for example an adjustable tap valve. The adjustment element is of pulse-feed type, with a predetermined duty cycle t%.

In FIG. 1 a collection element 17 is also shown, for example a wiper or so-called “squegee” associated with a suction device, which drains, as machine 1 progressively moves in the direction of arrow 2, the surplus treatment liquid 18 that soaks surface 12. Collection element 17 is connected hydraulically to a container 19 arranged for collecting residual liquid and possible dirt.

Collection element 17 can also be missing in certain models of machine.

As shown in FIG. 2, according to the present invention, a surface treatment machine 10, starting from surface treatment machine 1 of FIG. 1, is modified in order to comprise an adjustment element 26 arranged to feed adjustably the liquid supplied by reservoir 14 to the delivery mouth. The adjustment element 26 can be, for example, an adjustment valve electrically, or an electric pump with adjustable speed, of liquid pulse-feed type according to a predetermined duty cycle t%, which is the average ratio between the duration of a pulse of the pulse-feed step and the time between two consecutive pulses.

Furthermore, it comprises a sensor 20 configured to measure an operating parameter P of the machine, selected from the group consisting of: level of residual liquid in reservoir 14, liquid flow-rate from reservoir 14 towards delivery mouth 15, translation speed of the machine relatively to surface 12, or a combination thereof. Furthermore, it comprises a control unit 30 arranged to receive from sensor 20 a signal proportional to operating parameter P and configured to set the adjustment element 26 responsive to operating parameter P, in order to pulse-feed the liquid with a duty cycle t% according to a predetermined function f(P) of optimization of the flow-rate for maximizing the range of the machine.

With reference to FIG. 3, operating parameter P can be a measurement of the level of liquid present in reservoir 14. In this case, the sensor is, for example, a sensor 21 of a value P₁ which is relative to the amount of liquid present in reservoir 14. In this case, the duty cycle t% would be

t%=f(P₁)=K₁*P₁ ^(−1/2)  (1)

i.e. proportional to the reciprocal of the square root of the level.

For example, value P₁ which is relative to the amount of liquid present in reservoir 14 is a pressure value, and sensor 21 is a pressure sensor arranged to provide a signal of pressure P₁ that is communicating with a lower portion of reservoir 14. Such pressure sensor 21 is a sensor of the hydrostatic pressure directly related to the level of liquid surface 14 a.

In this case, the adjustment element 26 is selected from the group consisting of:

-   -   a piloted valve, where control unit 30 is configured to adjust         an opening section in a pulse-feed way of said valve with a duty         cycle t% in an increasing way responsive to decrease of pressure         P₁ according to function f(P₁);     -   a pump, where control unit 30 is configured to adjust the         flow-rate of the pulse-feed pump in an increasing way responsive         to decrease of pressure P₁ according to function f(P₁).

Such function can be, as shown above, an analytical function, which allows to calculate an adjustment parameter for each value of operating parameter P₁. Or it can be a table of values that associates to each pressure P₁, progressively decreasing, an adjustment parameter, for example an opening parameter, progressively increasing, of the piloted valve, or a number of turns, progressively increasing, of the pump.

Measuring the level P₁ is directly related to the volume of residual liquid, responsive to the geometry of the reservoir. This allows also to calculate the volume of residual liquid and then the range of the machine, versus volume. Such volume value can be advantageously, displayed on the machine, as useful information for operator. Owing to function f(P) the operator can then manage the residual range of the machine.

Alternatively, sensor 21 is a force sensor, for example a load cell, for example located under reservoir 14, or arranged to hold the weight of support elements of reservoir 14, capable of measuring instantly the weight of the reservoir, which changes from a value of weight equal to reservoir 14 full to a value of weight equal to reservoir 14 empty. The weight of the residual liquid is easily related both to the amount of residual liquid, useful as value of range of the machine, and to the level, for determining the adjustment parameter. Then, once determined the initial level from the measured weight, it is possible to calculate the formula (1) above indicated.

As further alternative embodiment, sensor 20 can be, in a way not shown, a level sensor, for example optical sensor, ultrasonic pulse sensor, electromagnetic, mechanical floating sensor located above or in the reservoir, and that is configured to measure the distance of the liquid surface 14 a of the liquid from the upper wall of reservoir 14.

Also in the latter two cases, responsive to a decrease of the weight of the reservoir or the level in the liquid surface 14 a, function f(P₁), in analytical form (1) or implemented as table, it provides increasing values of the adjustment parameter, i.e. of the duty cycle of the pulse-feed step, for each flow-rate value of liquid. Such flow-rate value can also be referred to a specific flow-rate, i.e. volume of liquid supplied for each surface unit covered by the machine.

In the exemplary embodiment of FIG. 4, operating parameter P is a direct measurement of the flow-rate of liquid that is supplied to delivery mouth 15, and the sensor is a flow-rate sensor 22, for example a flow meter, which is arranged in a portion of duct between reservoir 14 to delivery mouth 15, and provides a signal P₂ proportional to the flow-rate, and the adjustment element 26 is selected from the group consisting of:

-   -   a piloted valve, where control unit 30 is configured to adjust         an opening section of the valve in closed loop feedback of         liquid pulse-feed type, with a predetermined duty cycle t%,         according to a function f(P₂);     -   a pump, where control unit 30 is configured to adjust the speed         of the pump 26 of liquid pulse-feed type, with a predetermined         duty cycle t%, in closed loop feedback according to function         f(P₂).

Function f(P₂) can be expressed as:

t%=f(P₂)=K₂*P₂ ⁻¹  (2)

where the flow-rate P₂ is the flow-rate during feeding pulses.

In other words a pulse-feed rate is carried out as a succession of instants in which there is a measurable flow-rate and instants where the flow-rate is still, i.e. it is substantially the same as zero, and value P₂ is the flow-rate determined from the flow-rate sensor 22 when there is delivery, and the longer the duration of the pulse of delivery, with respect to the time between two pulses, the lower is the instantaneous flow-rate during feeding pulses.

This way, if for example the level in the reservoir decreases, owing to the hydrostatic pressure also the instantaneous flow-rate decreases, and then the duty cycle of the valve or the pump of pulse-feed type increases.

Then, control unit 30 has in memory a flow-rate threshold value, receives the actual flow-rate signal from the flow-rate sensor 22, then compares it with the flow-rate threshold value, and if the actual flow-rate signal is lower, it provides an adjustment parameter, such as an increased duty cycle of the piloted valve, or of the pulse-feed pump.

As shown in FIG. 5, operating parameter P can be, alternatively, a value P₃ proportional to a translation speed of the frame 11 with respect to surface 12 to treat. In this case, the sensor is a speed sensor 23 configured to provide a value P₃ proportional to the speed, the adjustment element 26 can be selected from the group consisting of:

-   -   a piloted valve, where control unit 30 is configured to adjust         an opening section of the liquid pulse-feed type valve, with a         predetermined duty cycle t%, in an increasing way responsive to         an increase of the speed according to a function f(P₃);     -   a pulse-feed pump with a predetermined duty cycle t%, where         control unit 30 is configured to adjust the duty cycle of the         pulse-feed pump in an increasing way responsive to an increase         of the speed according to function f(P₃),

wherein function f(P₃) can be expressed as:

t%=f(P₃)=K₃*P₃  (3)

In this embodiment, the frame 11 is configured to translate with respect to surface 12 to treat by means of wheels 40, and sensor 23 configured to provide a value P₃ proportional to a translation speed of the machine can be an encoder arranged to measure the speed of one of wheels 40.

For example, the higher the speed, function f(P₃), in the form of table or analytical function, provides increasing values of the adjustment parameter, in order to keep constant the amount of supplied liquid versus treated surface.

The translation can be carried out by pushing or in a motorized way. Such solution with encoder 23 on one of wheels 40 adjusts precisely the delivery of the treatment liquid even with translation by pushing, which can be particularly irregular, since that, with respect to a driven translation, the operator in a difficult way can keep a constant value of the speed.

In case of driven translation, as diagrammatically shown in FIG. 6, the frame 11 is configured to translate with respect to surface 12 to treat operated by a motor 50. Alternatively to the encoder described of FIG. 5, the sensor, in the case of FIG. 6, can be an amperometric sensor 24 arranged to measure, as parameter P₃ proportional to the speed, the pulse-width modulation (PWM) of the motor 50. Even in this case, the higher the driving current, function f(P₃), in the form of table or analytical function, provides increasing values of the adjustment parameter, in order to keep constant the amount of supplied liquid versus treated surface.

Operating parameter P can also be a combination of a measurement P₃ of the translation speed of the frame 11 and of a measurement P₁ of the level of liquid present in reservoir 14 or of a measurement P₂ of the flow-rate of liquid that is supplied to delivery mouth 15. In this case, function f(P) can be responsive to maximization of the range of the machine starting from settings of the machine given by the nature of the surface and/or by environmental conditions.

According to a further exemplary embodiment not shown in the figures, control unit 30 can be associated with a display unit of the operating parameters and of a value of range of the machine calculated on the basis of instant values of function f(P).

The adjustment element 26 of FIG. 2 can be a valve, for example a piloted valve, and reservoir 14 arranged with respect to delivery mouth 15 for delivering liquid to surface treatment element 13 by gravity through the adjustment valve 26. In this case, the control of level or flow-rate is essential to ensure an amount of liquid supplied that is constant, since the feeding by gravity is extremely affected by variation of level in the water reservoir.

In particular, the operator can set a value of range of the machine so that up to the next replenishment the flow-rate of liquid is constant and all the liquid present in the reservoir is used.

The foregoing description of specific exemplary embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt in various applications the specific exemplary embodiments without further research and without parting from the invention, and, accordingly, it is meant that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realize the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation. 

1. A surface treatment machine, comprising: a frame configured to translate with respect to a surface to treat, a surface treatment element connected to said frame and configured to treat with liquid a surface with respect to which said frame advances, a reservoir connected to said frame and arranged to provide liquid to said surface treatment element through a delivery mouth; an adjustment element arranged to adjustably pulse-feed the liquid provided from said reservoir to said delivery mouth; characterized in that it comprises furthermore: a sensor configured to measure an operating parameter P of said machine, selected from the group consisting of: level of liquid P₁ residual in the reservoir, actual flow-rate P₂ of the liquid from said reservoir towards said delivery mouth simultaneously to the pulses, speed P₃ of said machine relatively to said surface, or a combination thereof; a control unit arranged to receive from said sensor a signal proportional to said operating parameter P and configured to adjust said adjustment element responsive to said operating parameter P, in order to pulse-feed said liquid with a duty cycle t%, expressed as a ratio between the duration of a pulse of the pulse-feed step and the time between two consecutive pulses, determined according to a predetermined function t%=f(P) of optimization of the flow-rate, wherein said function f(P) is selected from the group consisting of: t%=f(P₁)=K₁*P₁ ^(−1/2)  (1) t%=f(P₂)=K₂*P₂ ⁻¹  (2) t%=f(P₃)=K₃*P₃  (3).
 2. Surface treatment machine according to claim 1, wherein said operating parameter P is a measurement of the level of liquid present in said reservoir, and said sensor is a sensor of a value P₁ proportional to said level of liquid present in said reservoir and said function f(P) is a function f(P₁) of optimization of the flow-rate calculated on said value P₁, said sensor selected from the group consisting of: a pressure sensor communicating with said reservoir and arranged to provide a signal of pressure owing to a liquid head starting from the liquid surface of said reservoir; a force sensor which can be arranged to hold the weight of support elements of said reservoir; a level sensor which is located in said reservoir, and configured to measure the distance of the liquid surface of the liquid from a bottom wall or from a top wall of said reservoir.
 3. Surface treatment machine according to claim 2, wherein said adjustment element is selected from the group consisting of: a piloted valve, wherein said control unit is configured to adjust an opening section in a pulse-feed way of said valve , with a predetermined duty cycle t%, by adjusting the time for opening said valve in an increasing way responsive to decrease of the level of liquid P₁ according to said function f(P₁); an adjustable pump, wherein said control unit is configured to cause the pump to pulse-feed the liquid, with a predetermined duty cycle t%, by adjusting a pulse-feed rate of said pump in an increasing way responsive to decrease of the level of liquid P₁ according to said function f(P₁).
 4. Surface treatment machine according to claim 1, wherein said operating parameter P is a measurement of the flow-rate P₂ of liquid that comes to said delivery mouth, and said sensor is a flow-rate sensor, which are located between said reservoir to said delivery mouth configured to provide a signal P₂ proportional to said flow-rate, said function f(P) being a function f(P₂) of optimization of the flow-rate calculated on said value P₂, and said adjustment element is selected from the group consisting of: a piloted valve, configured to pulse-feed the liquid, with a predetermined duty cycle t%, wherein said control unit is configured to adjust said duty cycle t% according to said function f(P₂); an adjustable pump, configured to pulse-feed the liquid, with a predetermined duty cycle t%, wherein said control unit is configured to adjust a pulse-feed rate of said pump according to said function f(P₂).
 5. Surface treatment machine according to claim 1, wherein said operating parameter P is a measurement of the translation speed of said frame with respect to said surface to treat, wherein said sensor is a speed sensor configured to provide a value P₃ proportional to said speed and said function f(P) is a function f(P₃) of optimization of the flow-rate calculated on said value P₃, said adjustment element selected from the group consisting of: a piloted valve, wherein said control unit is configured to pulse-feed the liquid, with a predetermined duty cycle t%, by adjusting the opening said valve with duty cycle t% increasing responsive to an increase of said speed according to said function f(P₃); an adjustable pump, wherein said control unit is configured to pulse-feed the liquid, with a predetermined duty cycle t%, wherein said control unit is configured to adjust a pulse-feed rate in an increasing way responsive to an increase of said speed according to said function f(P₃).
 6. Surface treatment machine according to claim 5, wherein said frame is configured to translate with respect to said surface to treat by means of wheels, and said sensor configured to provide a value P₃ proportional to a speed of said machine is an encoder arranged to measure the speed of one of said wheels.
 7. Surface treatment machine according to claim 5, wherein said frame is configured to translate with respect to said surface to treat operated by a motor, and said sensor configured to provide a value P₃ proportional to a speed of said machine is a sensor configured to measure the pulse-width modulation (PWM) of said motor.
 8. Surface treatment machine according to claim 2, wherein said operating parameter P is a combination of a measurement P₃ of the translation speed of said frame and of a measurement Pi of the level of liquid present in said reservoir or of a measurement P₂ of the flow-rate of liquid that comes to said delivery mouth, said function f(P) configured to maximize the range of the machine of said machine starting from settings of said machine given by the nature of said surface and/or by environmental conditions, said range of the machine being calculated as residual time or residual surface that can be treated by said machine before replenishment of liquid in said reservoir.
 9. Surface treatment machine according to claim 1, wherein said control unit is associated with a display unit of said operating parameter and of a value of range of the machine calculated on the basis of instant values of said function f(P), said range of the machine being calculated as residual time or residual surface that can be treated by said machine before replenishment of liquid in said reservoir.
 10. A method of treatment of surfaces, comprising the steps of: translating a surface treatment machine with respect to a surface to treat, said machine having a surface treatment element connected to a frame; feeding, at said surface treatment element, a treatment liquid, so that said surface treatment element treats with said liquid said surface during said translating; said treatment liquid being drawn from a reservoir connected to said frame, in order to provide said liquid to said surface treatment element through a delivery mouth; adjusting said delivery of liquid provided from said reservoir to said delivery mouth; characterized in that it comprises furthermore: measuring by a sensor an operating parameter P of said machine, selected from the group consisting of: level P₁ of residual liquid in the reservoir, actual flow-rate P₂ of the liquid from said reservoir towards said delivery mouth, speed P₃ of said machine relatively to said surface, or a combination thereof; wherein said adjusting is carried out on the basis of a signal proportional to said operating parameter P and of said adjustment element responsive to said operating parameter P, in order to pulse-feed said liquid with a duty cycle t%, expressed as a ratio between the duration of a pulse of the pulse-feed step and the time between two consecutive pulses, determined according to a predetermined function t%=f(P) of optimization of the flow-rate, wherein said function f(P) is selected from the group consisting of: t%=f(P₁)=K1*P₁ ^(−1/2)  (1) t%=f(P₂)=K₂*P₂ ⁻¹  (2) t%=f(P₃)=K₃*P₃  (3).
 11. Surface treatment machine according to claim 2, wherein the force sensor is a load cell.
 12. Surface treatment machine according to claim 2, wherein the level sensor is selected from the group consisting of: an optical sensor or ultrasonic pulse sensor or floating sensor.
 13. Surface treatment machine according to claim 4, wherein the flow-rate sensor is a flow meter or liter-counter. 